In recent years, web applications using web browsers have become common. Web applications include various types such as shopping sites, blogs, and bulletin boards.
Ordinarily, a program of a web application using a web browser operates on a server and the web browser only displays data and information that the program generates. As a result, if a communication device on which the web browser operates is not connected to the server, a problem occurs in which the web application cannot be used on the communication device.
To solve this problem, a system in which a web application provided by the server is executed off line has been contemplated (for example, refer to Patent Literature 1).
A transaction system using a web browser presented in Patent Literature 1 provides a client side that is a communication device with transaction software (a web server, a transaction processing section, and a database) that is used when the client is not connected to the network (in the off line state) such that the client can use the transaction system in the off line state. Thus, even if the client is off line, the client can use the transaction system.
The data base that the client of the transaction system uses while the transaction system is off line has a data update flag that denotes whether an update has been made. If data have been updated while the transaction system was off line, this data update flag denotes that data have been updated. Data having the data update flag that denotes that an update has been made are uploaded to the server such that data stored in the server and data stored in the client are synchronized.